Mechanically detachable vaso-occlusive device

ABSTRACT

A device for delivering an occlusive element includes an elongate pusher member having a lumen. A locking member is disposed within the lumen of the elongate pusher member. A moveable elongate releasing member is disposed within the lumen of the elongate pusher member. A filament is secured to the distal end of the elongate releasing member. The occlusive member is locked to the elongate releasing member when the filament passes through a securing member on the occlusive member and is pinched or wedged between the locking member and the elongate releasing member. The occlusive element is in an unlocked state when the elongate releasing member is retracted proximally relative to the elongate pusher member. The filament, along with the elongate releasing member, are retracted proximally until the filament is detached or uncoupled from the securing member of the occlusive member.

RELATED APPLICATION DATA

The present application claims the benefit under 35 U.S.C. § 119 to U.S.provisional patent application Ser. No. 60/866,590, filed Nov. 20, 2006.The foregoing application is hereby incorporated by reference into thepresent application in its entirety.

FIELD OF THE INVENTION

The field of the invention generally relates to systems and deliverydevices for implanting vaso-occlusive devices for establishing anembolus or vascular occlusion in a vessel of a human or veterinarypatient.

BACKGROUND OF THE INVENTION

Vaso-occlusive devices or implants are used for a wide variety ofreasons, including treatment of intra-vascular aneurysms. A commonvaso-occlusive device takes the form of a soft, helically wound coilformed by winding a platinum (or platinum alloy) wire strand about aprimary mandrel. The relative stiffness of the coil will depend, amongother things, on its composition, the diameter of the wire strand, thediameter of the primary mandrel, and the pitch of the primary windings.The coil is then wrapped around a larger, secondary mandrel, and againheat treated to impart a secondary shape. For example, U.S. Pat. No.4,994,069, issued to Ritchart et al., describes a vaso-occlusive coilthat assumes a linear, helical primary shape when stretched forplacement through the lumen of a delivery catheter, and a folded,convoluted secondary shape when released from the delivery catheter anddeposited in the vasculature.

In order to deliver the vaso-occlusive coils to a desired site, e.g., ananeurysm, in the vasculature, it is well-known to first position a smallprofile, micro-catheter at the site using a steerable guidewire.Typically, the distal end of the micro-catheter is provided, either bythe attending physician or by the manufacturer, with a selectedpre-shaped bend, e.g., 45°, 90°, “J”, “S”, or other bending shape,depending on the particular anatomy of the patient, so that it will stayin a desired position for releasing one or more vaso-occlusive coil(s)into the aneurysm once the guidewire is withdrawn. A delivery or“pusher” wire is then passed through the micro-catheter, until avaso-occlusive coil coupled to a distal end of the pusher wire isextended out of the distal end opening of the micro-catheter and intothe aneurysm. The vaso-occlusive device is then released or “detached”from the end pusher wire, and the pusher wire is withdrawn back throughthe catheter. Depending on the particular needs of the patient, anotherocclusive device may then be pushed through the catheter and released atthe same site.

One known way to release a vaso-occlusive coil from the end of thepusher wire is through the use of an electrolytically severablejunction, which is a small exposed section or detachment zone locatedalong a distal end portion of the pusher wire. The detachment zone istypically made of stainless steel and is located just proximal of thevaso-occlusive device. An electrolytically severable junction issusceptible to electrolysis and disintegrates when the pusher wire iselectrically charged in the presence of an ionic solution, such as bloodor other bodily fluids. Thus, once the detachment zone exits out of thecatheter distal end and is exposed in the vessel blood pool of thepatient, a current applied to the conductive pusher wire completes acircuit with an electrode attached to the patient's skin, or with aconductive needle inserted through the skin at a remote site, and thedetachment zone disintegrates due to electrolysis.

U.S. Pat. No. 5,122,136 issued to Guglielmi, et al. discloses a devicein which a portion of the guidewire connected between the tip and thebody of the guidewire is comprised of stainless steel and exposed to thebloodstream so that upon continued application of a positive current tothe exposed portion, the exposed portion is corroded away at least atone location and the tip is separated from the body of the guidewire.The guidewire and a microcatheter are thereafter removed leaving theguidewire tip embedded in the thrombus formed within the vascularcavity.

One perceived disadvantage with vaso-occlusive devices that are deployedusing electrolytic detachment is that the electrolytic process requiresa certain amount of time to elapse to effectuate release of thevaso-occlusive element. This time lag is also a perceived disadvantagefor vaso-occlusive delivery devices that utilize thermal detachmentmechanisms. U.S. Pat. No. 6,966,892 issued to Gandhi, et al. discloses avaso-occlusive device that uses a thermal detachment system.

Another detachment modality used to deploy vaso-occlusive elements usesmechanical detachment. U.S. Pat. No. 5,800,453 issued to Gia disclosesembolic coils that have a receiving slot on one end. A catheter controlwire or pusher guidewire having a hook which engages the coil'sreceiving slot is used as a coil pusher to eject the coil at the chosensite. The coils may also be placed within the lumen with a catheter in anose-to-tail fashion and pushed into the body lumen. Pushing the coilassembly via the pusher from the distal end of the catheter bodyuncouples the distal most coil.

Another example of a mechanical detachment system is disclosed in U.S.Pat. No. 5,800,455 issued to Palermo et al. Palermo et al. discloses adelivery system that includes a coil having a clasp or hook located atone end. The clasp or hook includes a passageway for a control wire. Theclasp interlocks with another clasp located on a distal end of a pushermember. The control wire is withdrawn in the proximal direction torelease the coil.

Still other mechanical detachments systems have been proposed that use afiber segment that is pulled in the proximal direction to decoupled thefiber from the embolic coil device. Examples of these systems may befound in U.S. Patent Application Publication Nos. 2006/0025803 A1(coiled fiber), 2006/0025802 A1 (U-shaped fiber), and 2006/0025801 A1(detachment filament).

One problem with certain existing mechanical detachment systems is thatthe junction between the embolic element and the releasing member movesduring the detachment process which may adversely impact the placementof the embolic element within the aneurysm. Another complication is thatmechanical detachment systems tend to have a stiff main section thatcomplicates accurate placement of the delivery system at the desiredlocation. Mechanical detachment systems also are perceived by physiciansas being harder to use than other devices. In addition, certainmechanical detachment systems may jeopardize the integrity of theembolic element (e.g. coil) after detachment.

There thus is a need for a vaso-occlusive delivery system that utilizesmechanical detachment yet does not suffer from the aforementioneddeficiencies. Such a system should be easy to use yet provide forconsistent detachment of embolic elements in the desired location.Moreover, the delivery system should be able to release the embolicelement without any recoil or other movement resulting from thedetachment operation.

SUMMARY

In one embodiment, a device for delivering an occlusive element such as,for example, a vaso-occlusive coil, includes an elongate pusher memberhaving a distal end and a proximal end and a lumen extending between thedistal and proximal ends. A locking member is disposed within the lumenof the elongate pusher member. An elongate releasing member is disposedwithin the lumen of the elongate pusher member. The elongate releasingmember has a proximal end and a distal end and is moveable within thelumen of the elongate pusher member (e.g. the elongate releasing membercan be moved proximally and distally along the long axis of the elongatepusher member). A filament is secured to the distal end of the elongatereleasing member. The occlusive member includes a securing memberdisposed at a proximal end thereof. The securing member of the occlusivemember is locked to the elongate releasing member when the filamentpasses through the securing member and is pinched between the lockingmember and the elongate releasing member. The occlusive element is in anunlocked state when the elongate releasing member is retractedproximally relative to the elongate pusher member. The filament, alongwith the elongate releasing member, are retracted proximally until thefilament is detached or uncoupled from the securing member of theocclusive member.

In one aspect of the invention, the locking member may include an edgeor surface that pinches or wedges the filament against the elongatereleasing member. In addition, the elongate releasing member may includea tapered distal end that engages with the edge or surface of thelocking member.

A blocking member may be disposed on the distal end of the elongatepusher member. The blocking member includes an aperture or passagewaydimensioned to permit passage of the filament but not the coil. Theblocking member thus prevents the coil from being retracted into theelongate pusher member.

Optionally, the elongate pusher member may include a coil memberdisposed on a distal end thereof. The coil member imparts addedflexibility to the distal region of the elongate pusher member.

In another aspect of the invention, a device of delivering an occlusiveelement such as, for instance, a vaso-occlusive coil includes anelongate pusher member having a distal end and a proximal end and alumen extending between the distal and proximal ends. A coil member issecured to the distal end of the elongate pusher member to give thedelivery device added flexibility at the distal end. An elongatereleasing member is disposed within the lumen of the elongate pushermember and is moveable within the lumen. The elongate releasing memberincludes proximal and distal ends with a filament being secured to thedistal end. The occlusive member includes a securing member disposed ata proximal end thereof. The securing member of the occlusive member islocked to the elongate releasing member when the filament passes throughthe securing member and is wedged between the locking member and theelongate releasing member. The occlusive element is in an unlocked statewhen the elongate releasing member is retracted proximally relative tothe elongate pusher member.

In still another aspect of the invention, a method of making avaso-occlusive coil includes the steps of loading a vaso-occlusive coilon a distal end of the elongate pusher member by passing a filamentcoupled to an elongate releasing member through a securing member of thevaso-occlusive coil. The vaso-occlusive coil is then locked to theelongate pusher member by advancing the elongate releasing memberdistally within the elongate pusher member so as wedge or pinch thefilament between the elongate releasing member and a locking surface ofthe elongate pusher member. For deployment, the vaso-occlusive coil isthen positioned adjacent to a deployment site such as, for instance, ananeurysm. The coil may be positioned by using a delivery catheter suchas, for instance, a microcatheter. The coil is then released byretracting the elongate releasing member proximally relative to theelongate pusher member. Proximal retraction of the elongate releasingmember eliminates the frictional pinching of the filament between thelocking surface and the elongate releasing member. The filament can thenbe withdrawn proximally (in response to movement of the elongatereleasing member) to de-couple from the securing member of the coil.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is partial cross-sectional view of a delivery device according toone embodiment.

FIG. 2 is a partial cross-sectional view of a delivery device accordingto another embodiment.

FIG. 3 is an enlarged cross-sectional view of the distal end of anelongate releasing member engaging with a locking member so as tofixedly secure a filament attached to the elongate releasing member.

FIG. 4 is a cross-sectional view of a distal portion of a deliverydevice according to another aspect of the invention.

FIG. 5 is a cross-sectional view of a blood vessel having an aneurysm. Adelivery device according to one embodiment is shown being deployedwithin a delivery catheter.

FIG. 6 is a partial cross-sectional view the distal end of a deliverydevice. FIG. 6 illustrates proximal retraction of the elongate releasingmember along with retraction of the filament. The filament is de-coupledfrom the coil.

FIG. 7 illustrates a cross-sectional view of a delivery device accordingto one embodiment. The filament coupled to the elongate releasing memberis shown passing through a lumen or passageway in the elongate pushermember.

FIG. 8 illustrates a force diagram of a cross-sectional view of a distalregion of a delivery device.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 illustrates a device 10 for delivering an occlusive element 12 toa vascular space such as, for example, aneurysm 100 (shown in FIG. 5).The occlusive element 12 may be formed as a vaso-occlusive coil 14created from a plurality of coil windings 16. When manufacturing thevaso-occlusive coil 14, the coil material is wound into a coil shape,which will typically be linear. Generally speaking, the coil 14 is ametallic coil made from a platinum alloy or a super-elastic alloy suchas titanium/nickel alloy, known as NITINOL. The diameter of the wireused in the production of the coils 14 may fall in the range of about0.00025 inches to about 0.006 inches. The coil 14 may have a primarydiameter of between about 0.003 and about 0.025 inches, but for mostneurovascular applications, a diameter between about 0.008 to about0.018 inches provides sufficient hoop strength to hold the coil 14 inplace within the chosen body site, lumen, or cavity, withoutsubstantially distending the wall of the site and without moving fromthe site as a result of the repetitive fluid pulsing found in thevascular system.

The axial length of the coil wire will usually fall in the range ofaround 0.5 to around 100 cm, more usually around 2.0 to 40 cm. Ofcourse, all of the dimensions provided above should be viewed only asguidelines, and the invention, in its broader aspects, should not belimited thereto. Dimensions that are suitable for use in occluding siteswithin the human body are included in the scope of this invention.

Depending on the desired therapeutic effect and the shape of the site tobe treated, the coil 14 may later be treated or accessorized in numerousways in order to enhance its therapeutic effect. The coil 14 may be madeto form various secondary shapes, often through the use of heattreatment, that may be better suited to fill a particular treatmentsite, as disclosed in U.S. Pat. Nos. 5,853,418 and 6,280,457, theentireties of which are expressly incorporated herein by reference.Alternatively, the coil 14 may have little or no shape afterintroduction into the vascular space, as disclosed in U.S. Pat. No.5,690,666, the entirety of which is expressly incorporated by referenceherein. In addition, external materials may be added to the outside ofthe coil 14 in an effort to increase its thrombolytic properties. Thesealternative embodiments are disclosed in U.S. Pat. Nos. 5,226,911,5,304,194, 5,549,624, 5,382,259, and 6,280,457, the entireties of whichare expressly incorporated herein by reference.

Still referring to FIG. 1, the proximal end 18 of the coil 14 includes asecuring member 20. The securing member 20 may be formed as a closedloop, hoop, ring, or eyelet. Alternatively, the securing member 20 maybe formed in an open configuration such as a hook or the like (notshown). The loop, hoop, ring, or eyelet from of the securing member 20has its two ends fixedly secured to a proximal end 18 of the coil 14. Inone embodiment, the securing member 20 may be formed integrally with thecoil 14. In this regard, the securing member 20 may be formed from aproximal winding of the coil 14. For example, the proximal winding maybe looped back upon itself and optionally bonded to one or more windings16 to form the closed securing member 20. Alternatively, the securingmember 20 may be formed separately from the coil 14. For example, thesecuring member 20 may be formed from a thin metal wire filament such asplatinum, NITINOL, titanium, stainless steel, and metallic alloys.Alternatively, the securing member 20 may be formed using apolymer-based material such as NYLON, PTFE, polypropylene, polyimide,PEEK, and the like. The separate securing member 20 may then be jointedto the proximal end 18 of the coil 14 either by tying or through abonding operation. For example, an adhesive material or a weld may beused to fixedly attach the securing member 20 to the proximal end 18 ofthe coil 14. If the securing member 20 is formed from a metallicmaterial, the securing member 20 may be formed from a thin metal sheetusing a photo-etching process. The liberated securing member 20 may thenbe jointed to the coil 14, for example, using a weld, solder, oradhesive.

Referring to FIG. 1, the delivery device 10 includes an elongate pushermember 30 having a proximal end 32 and a distal end 34. A lumen 36 isformed within the elongate pusher member 30. The elongate pusher member30 may be formed as a sheath, hypotube or the like. Alternatively, theelongate pusher member 30 may be formed at least in part from a coiledstructure created from a series of windings of material such as, forinstance, metallic coil. In yet another alternative, at least a portionof the elongate pusher member 30 may be formed from a braided materialto impart added flexibility. For example, a region near the distal end34 of the elongate pusher member 30 may be formed from a coil or braidto ensure flexibility at the distal tip of the delivery device 10. Instill another alternative, the distal end 34 of the elongate pushermember 30 may have a decreased stiffness as compared to the stiffness ofthe proximal end 32. For example, the distal end 34 of the elongatepusher member 30 may have a thinner wall thickness than the proximal end32.

The elongate pusher member 30 may be formed from a flexible yetlubricious polymer material such as polyimide, polytetrafluoroethylene(PTFE), polyetheretherketone (PEEK), fluorinated ethylene propylene(FEP), polypropylene, or the like. The elongate pusher member 30 mayalso be formed using non-polymer materials. For example, one or moresegments may be formed from metal hypotube formed from stainless steel,NITINOL, and the like. The elongate pusher member 30 generally has alength that permits the same to be advanced intravascularly to the siteof interest. For example, the elongate pusher member 30 has a length topermit the distal end 34 to be positioned adjacent to the delivery site(e.g., aneurysm 100) while the proximal end 32 is positioned outside thepatient's body. A typical range of lengths for the elongate sheath 30may include between about 1.25 to about 2.0 meters.

As seen in FIG. 1, a blocking member 38 is disposed at the distal end 34of the elongate pusher member 30. The blocking member 38 includes anaperture 39 sized to permit passage of a filament 48 (described in moredetail below). The size of the aperture 39 is dimensioned such that thefilament 48 can pass through but not the coil 14. In some cases, theaperture 39 may be dimensioned to permit passage of at least a portionof the securing member 20. However, the aperture 39 still prevents thecoil 14 from retracting inside the elongate pusher member 30. Theblocking member 38 may be formed from a short segment of tubing such as,for instance, stainless steel hypotube, or a polymer-based tube (e.g.,polyimide, PEEK, or the like). Alternatively, the blocking member 38 maybe formed from a short segment of coil (not shown) that resides insidethe lumen 36 of the elongate pusher member 30. The blocking member 38may be bonded or jointed to the elongate pusher member 30 using anadhesive, solder, or weld. In addition, it is also contemplated that theblocking member 38 may abut against the distal end 34 of the elongatepusher member 30.

The device 10 includes an elongate releasing member 40 disposed withinthe lumen 36 of the elongate sheath 30. The elongate releasing member 40has a distal end 42 and a proximal end 44. The elongate releasing member40 is formed from a flexible yet sturdy material that providessufficient columnar strength to avoid breakage during the deploymentprocess. For example, the elongate releasing member 40 may be formedfrom a wire made from a metal or alloy such as NITINOL, titanium,stainless steel or the like.

As seen in FIGS. 1-7, the elongate releasing member 40 includes atapered section 46 located at the distal end 42. The tapered section 46may be formed by grinding a wire or the like. As described in moredetail below, the tapered section 46, pushes the filament 48 against alocking member 60 and is used as an engaging surface to temporarily lockthe elongate releasing member 40 relative to the elongate pusher member30. The filament 48 is pinched between the tapered section 46 andlocking member 60 and is prevented from moving distally so as to keepthe coil 14 from being released prematurely.

Still referring to FIG. 1, a locking member 60 is provided inside thelumen 36 of the elongate pusher member 30. The locking member 60 islocated near the distal end 34 of the elongate pusher member 30 and maybe formed as a tube or coil. For example, the locking member 60 may beformed from a short segment of stainless steel or NITINOL hypotube.Alternatively, the locking member 60 may be created from a short segmentof stainless steel or platinum coil. The locking member 60 may be bondedor jointed to the interior of the elongate pusher member 30 using aweld, solder, adhesive, or the like. The locking member 60 includes anlocking surface 60 a (FIG. 3) that contacts the tapered section 46 ofthe elongate releasing member 40 during the locking operation.

In still another aspect of the invention, the locking surface 60 a maybe integrated directly into the elongate pusher member 30. For example,the locking member 60 may be formed as part of the elongate pushermember 30.

As seen in FIG. 1, a filament 48 is disposed on the distal end 42 of theelongate releasing member 40 and includes a proximal end 50 and a distalend 52. The filament 48 is used to releaseably secure the coil 14 to theelongate releasing member 40. The filament 48 may be formed as a string,wire, or cable. For example, the filament 48 may be formed from ametallic material such as, for instance, NITINOL, stainless steel, ortitanium. Alternatively, the filament 48 may be formed from a polymermaterial such as polyethylene terephthalate (PET), fluorinated ethylenepropylene (FEP), polypropylene, polyethylene napthalate (PEN), or thelike. Of course, other materials beyond those expressly listed above mayalso be used. The filament 48 may constructed of a single strand or maycomprise multiple strands in a braided or wound configuration.

The length of the filament 48 may vary. For example, the filament 48 maybe formed from a relatively short segment such as in the embodimentsillustrated in FIGS. 1-6. Alternatively, the length of the filament 48may be relatively long such as disclosed in the embodiment shown in FIG.7. The filament 48 should have a length that permits the same to passthrough the securing member 20 and backtrack proximally with respect tothe locking member 60 to permit locking. The proximal end 50 of thefilament 48 may be secured to the distal end 42 of the elongatereleasing member 40 by a weld, adhesive, or the like. Alternatively, theelongate releasing member 40 and filament 48 can be integrated into orformed having a unitary construction. For example, a single wire may beused that has a relatively thick proximal section 40, a tapered section46, and a thin filament 48.

The elongate releasing member 40 is moveable (e.g., slidable) within thelumen 36 of the elongate pusher member 30. The elongate releasing member40 is moveable between a locked configuration and an unlockedconfiguration. FIGS. 1-5 and 7 illustrates the elongate releasing member40 being advanced distally to “lock” the coil 14 to the elongate pushermember 30. Referring to FIG. 1, the filament 48 that is secured to thedistal end 42 of the elongate releasing member 40 passes through thesecuring member 20 located on the coil 14 and returns along side aportion of the elongate releasing member 40. The filament 48 is thuswedged or pinched between the locking member 60 and the tapered section46 of the elongate releasing member 40. FIG. 3 illustrates a magnifiedview of the filament 48 being pinched or wedged between the lockingmember 60 and the elongate releasing member 40.

In the locked configuration, the coil 14 is securely fastened to thefilament 48. Frictional engagement of the filament 48 between thelocking member 60 and the elongate releasing member 40 thus prevent thefilament 48 from retracting through the securing member 20 of the coil14. While FIGS. 1-3 and 5-7 illustrate the locking member 60 having alocking surface 60 a in the shape of an edge (shown best in FIG. 3) thatforms as a pinch point, it should be understood that a surface may alsobe used as the pinch point. For example, FIG. 4 illustrate oneembodiment of a locking member 60 in which an angled surface is used asthe locking surface 60 a to secure the filament 48.

In one embodiment, a tight or friction fit is formed between theelongate releasing member 40 and the locking member 60, therebyrequiring a certain threshold amount of retracting force (in theproximal direction) before the elongate releasing member 40 can moverelative to the elongate pusher member 30. To illustrate a self-lockingmechanism of the type described herein, FIG. 8 illustrates a forcediagram that shows the various forces imparted to the filament 48. Whenthe occlusion coil 14 is pulled away (distally) from the elongate pushermember 30 by a force F, it transforms into forces F₁ and F₂ on the twosegments of filament 48′ and 48″ passing through securing member 20. F₁will then pull the tapered section 46 toward the locking member 60 andgenerate compressive forces N₁ and the resultant reaction force N₂. N₁will then generate friction force f₁, wherein f₁=frictioncoefficient×N₁. When f₁ is greater than or equal to F₂, the filamentmember 48″ will not be pulled away from its position, thus ensuring alocked configuration of the coil 14.

As seen in FIGS. 1, 2, and 7, the proximal end 32 of the elongate pushermember 30 includes a locking member 90. The locking member 90 is used tofixedly secure the elongate releasing member 40 relative to the elongatepusher member 30. This may be accomplished by the use of a cap or thelike such as that illustrated in FIG. 1 that is bonded or otherwiseengaged with the elongate releasing member 40. For example, the elongatepusher member 30 may have a series of threads 35 on the exterior surfacethat engage with corresponding grooves 92 in the locking member 90. Inthe configuration shown in FIG. 1, the locking member 90 includes acompressible O-ring 94. When the locking member 90 is screwed onto theproximal end 32 of the elongate pusher member 30, the O-ring 94undergoes radial expansion and grips the elongate releasing member 40.In this regard, the elongate releasing member 40 cannot be moved ineither the proximal or distal directions. In order to deploy the coil14, the locking member 90 must first be released from the elongatepusher member 30 by unscrewing the same from the threads 35.

FIG. 2 illustrates an alternative embodiment of a delivery device 10.This embodiment is similar to the embodiment illustrated in FIG. 1 withthe exception that a coil member 70 is secured to the distal end 34 ofthe elongate pusher member 30. The coil member 70 may be formed from aplurality of windings 72 of wire (e.g., metallic or alloy such asplatinum, stainless steel, titanium, and the like). The coil member 70may be flexed about the its long axis such that the delivery device 10incorporating this feature has added flexibility to reduce microcatheterrecoil or kick-back. The coil member 70 may be coated or otherwiseencapsulated in a sheath (not shown in FIG. 2). The coil member 70 mayinserted into the lumen 36 of the elongate pusher member 30 (not shown).In this regard, a proximal end 74 of the coil member 70 may be bonded toan interior surface of the elongate pusher member 30. The coil member 70may be bonded using a weld, solder, adhesive, or other known technique.Alternatively, as is shown in FIG. 2, the coil member 70 may abutagainst the distal most end 74 of the elongate pusher member 30. Asurrounding jacket or sheath 78 may be used to secure the coil member 70to the elongate pusher member 30. Still referring to FIG. 2, theblocking member 38 is disposed in a distal end 76 of the coil member 70.The blocking member 38 may be bonded to the coil member 70 via a weld,solder, or the use of an adhesive or other bonding agent.

FIG. 5 illustrates a process of delivering the coil 14 to an aneurysm100 in a blood vessel 110. As seen in FIG. 5, a catheter device 90 suchas a microcatheter is positioned within the vessel 110 so as to placethe distal tip adjacent to the entry point or neck of the aneurysm 100.The device 10 of the type described herein is then advanced through thecatheter 90. The device 10 is advanced to place the coil 14 located atthe distal end of the elongate pusher member 30 at least partiallywithin the aneurysm 100. One or more radiopaque markers (not shown)located on the catheter 90 and/or elongate pusher member 30, or on theelongate releasing member 40, may be used to aid the physician inpositioning the device 10 for deployment of the coil 14.

The coil 14 may be loaded onto the delivery device 10 by passing thedistal end 52 of the filament 48 through the securing member 20 of thecoil 14. The elongate releasing member 40 may need to be partiallyadvanced within the lumen 36 of the elongate pusher member 30 to ensurethere is enough length of available filament 48. The distal end 52 ofthe filament 48 is pulled back proximally through the blocking member 38and the locking member 60. When the distal end 52 of the filament 48 isproximal to the locking member 60, the elongate releasing member 40 isadvanced distally so as to pinch the filament 48 between the taperedsection 46 and the locking member 60. In the locked state, the elongatereleasing member 40 is in a compressive state so as to fixedly secure orpinch the filament 48 against the locking member 60. The coil 14 is nowlocked relative to the elongate pusher member 30.

FIG. 7 illustrates one alternative embodiment in which the filament 48is fed through passageway 82 in the elongate pusher member 30. Thefilament 48 then exits the passageway 82. In this embodiment, thefilament 48 can be pulled taut during the loading of the coil 14. Inparticular, the filament 48 may be pulled proximally while the elongatereleasing member 40 is advanced distally to lock the filament 48 intoplace. Any extra length in the filament 48 which protrudes from theelongate pusher member 30 can be clipped or trimmed off as appropriate.

In one embodiment, a locking member 90 located on the proximal end 32 ofthe elongate pusher member 30 may temporarily secure the elongatereleasing member 40. Namely, the cap may prevent the elongate releasingmember 40 from accidentally being withdrawn in the proximal direction,thereby causing premature release of the coil 14. The mechanical lock(e.g., cap) may be twisted, unscrewed or otherwise removed or unloosenedto permit movement between the elongate pusher member 30 and theelongate releasing member 40. In another alternative, an adhesive, epoxyor glue may be used to temporarily lock the elongate releasing member 40relative to the elongate pusher member 30. The temporary locking statebetween the elongate releasing member 40 and the elongate pusher member30 may be opened by pulling the elongate releasing member 40 proximallyrelative to the elongate pusher member 30. For example, the adhesivebond may be broken once a certain level of retracting force is appliedto the elongate releasing member 40.

FIG. 6 illustrates the deployment of the coil 14 from the deliverydevice 10. Deployment is initiated by retracting the elongate releasingmember 40 in the proximal direction relative to the elongate pushermember 30. For example, a physician may hold the elongate pusher member30 with one hand while using the other hand to pull or retract theelongate releasing member 40. When the elongate releasing member 40 isretracted proximally, the filament 48 is no longer wedged or pinchedbetween the tapered section 46 and the locking member 60. In thisregard, the filament 48 can be withdrawn through the securing member 20of the coil 14. The coil 14 is fully released when the filament 48completely retracts from the securing member 20 as is illustrated inFIG. 6.

Once the coil 14 is released from the delivery device 10, the elongatepusher member 30 may then be retrieved from the body by withdrawing theelongate pusher member 30 together with the elongate releasing member 40and attached filament 48 in the proximal direction. If additional coils14 need to be deployed, then another delivery device 10 with a coupledcoil 14 may be advanced through the catheter 90 as described above.After all the coil(s) 14 have been deployed, the catheter 90 is thenwithdrawn from the vessel 110.

One advantage of the delivery device 10 described herein is that apull-to-release process is used to deploy the coil 14. Because a pullingmotion is used, there is no risk of poking or puncturing the aneurysm100 that is inherent in push-based delivery devices. In this regard, thedetachment of the coil 14 from the filament 48 is atraumatic. Inaddition, because the coupling between the coil 14 and the elongatereleasing member 40 is mechanical, detachment is faster thanelectrolytic-based delivery devices. Finally, the nature of couplingbetween the coil 14 and the elongate releasing member 40 produces asmooth release of the coil 14 during deployment. For example, thedelivery device 10 has reduced kick-back or recoil.

While embodiments of the present invention have been shown anddescribed, various modifications may be made without departing from thescope of the present invention. The invention, therefore, should not belimited, except to the following claims, and their equivalents.

1. A device for delivering an occlusive element comprising: an elongate pusher member having a distal end and a proximal end and a lumen extending between the distal and proximal ends; a locking member disposed in the lumen of the elongate pusher member; an elongate releasing member having a distal end and a proximal end, the distal end including a filament attached thereto, the elongate releasing member being moveable within the lumen of the elongate pusher member; and an occlusive element including a securing member positioned at a proximal end, wherein the securing member is locked to the elongate releasing member when the filament passes through the securing member and is pinched between the locking member and the elongate releasing member and unlocked when the elongate releasing member is retracted proximally relative to the elongate pusher member.
 2. The device of claim 1, wherein the locking member includes one of an edge or surface that pinches the filament against the elongate releasing member.
 3. The device of claim 1, the elongate releasing member including a tapered portion, wherein the filament is pinched between the tapered portion and the locking member in a locked configuration.
 4. The device of claim 1, further comprising a blocking member disposed at a distal end of the elongate pusher member, the blocking member including an aperture dimensioned to receive the filament but prevent passage of the securing member.
 5. The device of claim 1, the distal end of the elongate pusher member having a stiffness that is less than the stiffness of the proximal end of the elongate pusher member.
 6. The device of claim 5, wherein the distal end of the elongate pusher member comprises a coil member.
 7. A device for delivering an occlusive element comprising: an elongate pusher member having a distal end and a proximal end and a lumen extending between the distal and proximal ends; a coil member secured to the distal end of the elongate pusher member; a locking member disposed in the lumen of the elongate pusher member; an elongate releasing member having a distal end and a proximal end, the distal end including a filament attached thereto, the elongate releasing member being moveable within the lumen of the elongate pusher member; and an occlusive element including a securing member positioned at a proximal end, wherein the securing member is locked to the elongate releasing member when the filament passes through the securing member and is wedged between the locking member and the elongate releasing member and unlocked when the elongate releasing member is retracted proximally relative to the elongate pusher member.
 8. The device of claim 7, wherein the locking member includes one of an edge or surface that pinches the filament against the elongate releasing member.
 9. The device of claim 7, the elongate releasing member including a tapered portion, wherein the filament is wedged between the tapered portion and the locking member in a locked configuration.
 10. The device of claim 7, further comprising a blocking member disposed at a distal end of the coil member, the blocking member including an aperture dimensioned to receive the filament but prevent passage of the securing member.
 11. The device of claim 10, wherein the blocking member is disposed inside a lumen of the coil member.
 12. A method of making a vaso-occlusive coil delivery device comprising: loading a vaso-occlusive coil on a distal end of an elongate pusher member by passing a filament coupled to an elongate releasing member through a securing member of the vaso-occlusive coil; and locking the vaso-occlusive coil to the elongate pusher member by advancing the elongate releasing member distally within the elongate pusher member so as to wedge the filament between the elongate releasing member and a locking surface of the elongate pusher member.
 13. The method of claim 12, wherein the locking surface of the elongate pusher member comprises a locking member disposed within a lumen of the elongate pusher member.
 14. The method of claim 12, wherein the elongate pusher member includes a flexible distal end.
 15. The method of claim 12, wherein a blocking member is disposed at a distal end of the elongate pusher member, the blocking member including an aperture dimensioned to receive the filament but prevent passage of the securing member.
 16. The method of claim 12, wherein during the step of loading the vaso-occlusive coil, the filament is retracted proximally.
 17. A method of deploying a vaso-occlusive coil from a delivery device according to claim 12, further comprising: positioning the vaso-occlusive coil adjacent to a deployment site; and retracting the elongate releasing member proximally relative to the elongate pusher member so as to release the vaso-occlusive coil from the filament.
 18. The method of claim 17, further comprising the step of removing the elongate pusher member from a patient.
 19. The method of claim 17, further comprising locking the elongate releasing member relative to the elongate pusher member after loading the vaso-occlusive coil.
 20. The method of claim 19, further comprising unlocking the elongate releasing member relative to the elongate pusher member prior to release of the vaso-occlusive coil. 